Process and apparatus for cleaning exhaust fumes

ABSTRACT

A process and apparatus for cleaning exhaust fumes from a combustion device by flow through a moving filter that is continually cleaned by air flowing through the filter, in the direction opposite to the flow of exhaust fumes therethrough, and thence into the combustion device for reburning of certain fume products captured by the filter.

United States Patent Bauman 1 1 Sept. 30, 1975 [54] PROCESS AND APPARATUS FOR 2.865,61l 12/1958 Bentele 60/39.51 H 2,893,697 7/1959 Hryniszak 1. 60/3951 H 2,895,296 7/1959 Hryniszak 60/3951 1-1 [76] Inventor: Dieter Bauman, Nachtigallenstrasse 3 050 375 8/19 3 Bloch 60/280 60, 6078 Ncu lsenburg 2, Germany 3293.831 12/1966 Hollyday 1 1 55/290 3.607.133 9/1971 Hirao et al.. 60/902 X [221 Flcdl July 3.641.763 2/1972 C016 60/3951 11 [21] Appl. No.: 377,959

Primary E.\'aminerWi1liam L. Freeh 1521 US. (:1. 60/280; 60/295; 60/299; jff f f j g f; h

23/288 F; 55/290; 55502 tune gen 0/ 1//n n rew renc [51] Int. Cl. FOIN 3/15 [58] Field of Search 60/3951 1-1, 902, 295. 299, [57] ABSTRACT 60/291 288; 23/288 F; 55/290 A process and apparatus for cleaning exhaust fumes DIG. 30 from a combustion device by flow through a movmg filter that is continually cleaned by air flowing through [56} References cued the filter, in the direction opposite to the flow of ex- UNITED STATES PATENTS haust fumes therethrough, and thence into the com- 1.893372 1/1933 Kryzanowsky 60/288 X bustion device for rebuming of certain fume products 2.374.608 4/1945 McCollum 60/902 X captured the filter. 2 792 909 5/1957 Court v 60/280 214461.195 8/1958 Alcock 60/3951 H 2 Claims, 10 Drawing Figures I i: I AIR MIX AIR IN 001413030011 DEVICE 700 PURIFIED EXHAUST 1 EXHAUST F l LT E R DEVICE U.S. Patent Sept. 30,1975 Sheet 1 of7 3,908,367

US. Patent Sept. 30,1975 Sheet2of7 3,908,367

US. Patent Sept. 30,1975 Sheet 3 of7 3,908,367

U.S. Patent Sept. 30,1975. Sheet40f7 3,908,367

US. Patent Sept. 30,1975 Sheet 5 of7 3,908,367

Sheet 6 of 7 l I I l l l I l l US. Patent Sept. 30,1975

U.S. Patent Sept. 30,1975

Fig. 9

705 I {4+ AlR MIX COMBUSTION Y DEVICE E ExHAusT,

Sheet 7 0f 7 AIR IN PURIFIED EXHAUST BACKGROUND AND SUMMARY OF THE INVENTION This invention relates in general to the cleaning of exhaust fumes such as are emitted by internal combustion engines, furnaces, chemical reactors and other combustion devices.

At present, the need for cleaning exhaust fumes to remove therefrom certain toxic components as contribute to air pollution is well recognized.

Treatment of exhaust fumes can be effected by passing the fumes through different known types of filters, preferrably those of the catalytic type which very effectively convert toxic components into harmless, or less toxic products. Filtering of fumes is recognized as one way to clean them, even if only unbumt carbon or metal particles are kept from discharge into the atmosphere. In certain cases, it is advantageous to return fume components, such as unbumt solids, to the combustion device for reburning therein.

Several kinds of catalytic filters, known in the prior art, have been tested for the cleaning and reburning of exhaust fumes of internal combustion engines and other devices. These filters have been applied in such a way that the exhaust fumes are passed through in one direction, exposing the entire filter surface. Running tests have shown that such filters become relatively soon obstructed, whereby either the rate of flow or the catalytic reaction will be reduced.

The invention solves such problem by utilizing filtering action in two directions of flow, whereby the engine air intake passes through the filter in one direction and adjacent separately, the exhaust fumes pass through the filter in the opposite flow direction, interchangeably. This system offers the advantage that the exhaust deposition on the filter will be blown free through the air intake, and incompletely catalyzed substances will be recirculated to the combustion chamber for total oxidapath extending through a filter to clean said exhaust fumes by removing certain components thereof by re- .action with the area of the filter intercepted by said first flow path; passing air into the combustion device along a second flow path, separate from said first flow path and extending through and intercepting another area of said filter to clean, by reaction with such air, the filter area intercepted by said second flow path, said air passing through the filter in a direction opposite to the flow of the exhaust fumes through the filter; and cyclically moving said filter relative to said first and second flow paths to successively present for interception with said second flow path those areas of the filter previously intercepted by said first flow path, whereby the areas of the filter contaminated by reaction with the exhaust fumes are decontaminated by reaction with the air, and decontaminated areas of the filter are presented in succession for cleaning the exhaust fumes. Depending upon specific requirements, the filter can be one that catalytically reacts with at least one component of the exhaust fumes, or the filter can be merely a mechanical trap that catches solids. One of the advantages of the invention is that the filter will trap solid particles entrained in the exhaust fumes, and these trapped particles will be removed by the opposite direction air flow through the filter and carried thereby into the combustion device for reburning.

According to one embodiment of the invention, energy is extracted, as by means of a turbine, from the exhaust fumes flowing along the first flow path to drive the filter.

For carrying out the aforesaid process, the invention provides an apparatus comprising a first conduit means, a second conduit means, a moveable filter, and means for cyclically moving the filter. The first conduit means defines a first flow path communicating with the combustion device to receive exhaust fumes outflowing therefrom. The second conduit means defines a second flow path communicating with the combustion device to deliver an intake gas fiow thereto. The filter is disposed for movement relative to the first and second conduit means, and is positioned to intercept the first and second flow paths, the area of the filter intercepted by the first flow path being operable to clean exhaust fumes flowing in a given direction through the filter, and the area of the filter intercepted by the second flow path being cleaned by the intake gas flowing in the opposite direction through the filter. The means for cyclically moving the filter assures that the areas thereof contaminated by fume products will be cleaned before returning into the fume flow. In practice, the filter is expediently in the form of a rotatable disc, ring, or cup,

or anendless belt supported on drive drums.

For a better understanding of the invention and its several potential applications and advantages, reference should be had to the following detailed description and accompanying drawings which together exemplify certain preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic elevation view, partly in section, of an internal combustion engine equipped with a fume cleaning apparatus according to a preferred embodiment of the invention.

FIG. la is an end view, partly broken away. taken in the indicated direction I in FIG. 1, to show details of the filter drive mechanism.

FIG. 2 is a schematic plan view showing how the fume cleaning apparatus of FIG. 1 is installed for use in a typical automotive vehicle.

FIG. 3 is a cross-sectional view of a fume cleaning apparatus according to another embodiment of the invention.

FIG. 4'is another cross-sectional view of the fume cleaning apparatus shown in FIG. 3, as taken along line IVIV therein, with FIG. 3 being related to FIG. 4 as taken along the line lII-III therein.

FIG. 5 is a schematic side view, partly broken away, of a fume cleaning apparatus according to a further embodiment of the invention.

FIG. 6 is a schematic perspective view of the fume cleaning apparatus shown in FIG. 5.

FIG. 7 is a typical cross-section taken through the thickness of a filter that can be used in the fume cleaning apparatus of the invention.

FIG. 8 is a perspective exploded view of another type of filter that can be used in the fume cleaning apparatus of the invention.

FIG. 9 is a schematic diagram illustrating how the fume cleaning apparatus and method of the invention can be applied in general to any combustion device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The internal combustion engine 10 is shown schematically in FIG. 1 with combustion chamber 11 extending above exhaust valve 12, connecting to exhaust port 13 into built-in muffler 14, attached to fume cleaning apparatus 15 of the invention, with the actual tailpipe 16. An exhaust pressure-driven turbine 17 drives the filter of apparatus 15 via flexible shaft 18.

In parallel to the exhaust system elements 13-16 is the intake system 19, located so as to lead to carburetor 20, which is conventionally connected to the intake valve, leading to chamber 11.

Fume cleaning apparatus 15 has a housing 21, containing filter disc 22. The filter disc 22 is held in place through a ring with teeth that engage worm gear 24, attached to flexible shaft 18.

Filter disc 22, which preferreably contains catalytic material, will thus be continuously rotated.

As will be appreciated by the artisan, the rotating filter-ring area in the disc 22 is subjected to continuous deposition with exhaust fume components, particularly solids. The same filter area will be, with each revolution, exposed through the air intake in the opposite flow direction.

All parts shown in FIG. 2 are designated the same as in FIG. 1.

The intake line 19, as shown in FIG. 2, represents a bypass of the air intake system, whereby the air intake partially passes through the conventional air filter 25. In the event that the entire air intake is regulated through the intake line 19, the filter 22 takes over the function of filter 25, which no longer serves its purpose. Under this working condition, it becomes obvious that the air contaminants deposited on the filter surface will continuously be blown free through the exhaust.

In FIG. 2, at the exhaust pipe 16, a pressure relief valve 26 has been indicated, which will open in case of overload or blockage of filter 22 and release the exhaust through line 27.

The FIG. 1 filter 22, for example, is shown in the form of a disc, whereas in FIGS. 3 and 4, a filter 32 which performs the same function is shown as having a pot or cup configuration, and is located in a housing 31. The exhaust port 33 is connected to the exhaust line 36.

The intake line is shown as 39 and the part of the intake line leading to the carburetor is shown as 38. The filter 32 is fastened to driveshaft and rotatably driven thereby. The effective area of the catalytic filter is in the protruding rim section 34. The radial webs 35 function to provide structural reinforcement for filter 32 as well as baffles forming four separate chambers that prevent cross-flow between intake and exhaust lines regardless of the orientation of filter 32 about the driveshaft 30 axis. The arrows 37 indicate the flow direction of the exhaust and intake respectively.

By way of example, in FIGS. 5 and 6, the filter is shown as an endless belt 40, wherein catalytically reactive filter media has been applied to a porous substrate. Belt 40 is driven by and over the rotatable drums 41 and 42. Between drums 41 and 42 is a baffle 43 located in such a way as to form two chambers, one of which communicates with an exhaust line 44, and the other of which communicates with an intake line 45. Exhaust line 46 and intake line 47 communicate with corresponding chambers associated with exhaust and intake lines 44 and 45 respectively. It is to be understood that there is a housing surrounding and containing belt 40 and drums 41 and 42 so that in both the intake and exhaust sides there is flow through the filter belt 40.

The effectiveness of the moving filter belt 40, is essentially the same as that described in the example in FIG. 6, shown schematically in isometric view. The pipelines 46 and 47 in FIG. 5 represent the same lines shown in FIG. 6 as 46a and 47a respectively. However, the difference is that in the FIG. 6 example, the lines 46a and 47a lead into the drums 41, 42 instead of leading into chambers defined by baffle 43 and these drums 41, 42. In the FIG. 5 example, the exhaust flow is from one of the exhaust lines 44, 46 to the other-through the belt 40, and the intake flow is from one of the intake lines 45, 47 to the other through a separate area of belt 40. The same basic intake and exhaust flow pattern is used in the FIG. 6 example, as between lines 44, 46a, and lines 45, 47a, with the variation that both flows pass through drums 41, 42.

For such purpose, in the FIG. 6 example the drums 41, 42 have hollow driveshafts communicating with corresponding lines 46a and 47a, and have portholes that allow radial flow into the chamber area formed by individually spaced disc 48 mounted on these driveshafts. If desired, drums 41, 42 with porous walls can be substituted.

It is also possible to fabricate the discs 48 from catalytically reactive materials to increase the effectiveness of the entire arrangement.

FIGS. 7 and 8 show a design example of the inventive arrangement for catalytic filters. The schematic crosssection in FIG. 7 shows the filter 50, made as a ceramic body in which catalytically reactive metallic fibres are imbedded in an inorganic porous material, whereby the density increases in the direction indicated by arrow 51, which means that the pores become smaller in that direction. The filter may also be made homogeneously, or may be composed of individual layers from 52 to 55 with different properties.

FIG. 8 illustrates the filter 60, composed of different mesh size wire cloth, 61 to 64. Here, also the density increases in the direction of arrow 60, while the pores become smaller. In both filters and 60, the flow is such that the exhaust fumes first come in contact with the coarser openings, and then the finer ones.

For guidance in the choice of catalytic materials effective against particular exhaust fume components, reference should be had to the series of volumes entitled Vehicle Emissions, Parts I, II and III, published by the Society of Automotive Engineers, Inc., of New York, NY.

Known catalytic reactive filters are composed from a variation of ceramic and/or metallic materials sintered together or melted with a ceramic binder. By blending in organic particles, which are burned out during the sintering or melting process, a controlled porosity or density filter can be created. According to the composition of fumes to be catalyzed, catalytic reactive metals may be deposited by electroplating at the pore surface of the filter material, which increases the reactivity of the catalytic surface.

The pore-forming organic particles needed for the filter discs may be added stepwise in layers by increasing the particle size, so that the exhaust fumes enter the larger porous surface first and then pass through the finer pores, or the filter may be composed of discs of different size porosity. This will cause an internal entrapment ranging from unburned carbon particles, reduced down to carbon monoxide, which may either escape as detoxified gas, through the fine porous side of the filter, or may be returned through the moving filter into the engine air intake and combustion chamber for additional oxidation, or further size reduction, until it may also pass in the form of non-toxic gas through the fine porous side of the filter. This interchanging process prevents the catalytic filter element from clogging up. In the event of sudden unexpected blockage from unburned fuel, caused by ignition failure, the exhaust will then be released directly through a pressure relief valve. In low operating exhaust temperature areas, a transport belt made of fine metal mesh or of hightemperature resistant porous plastic materials such as teflon in felt or woven form, may also be used. This porous transport belt, as shown in FIGS. 5 and 6, will be driven over two or more drums. The intake or exhaust passes through the hollow drive or idling shafts, seperated into chambers with the porous belt.

In all embodiments of the invention, the exhaust deposition and removal follows the same basic process.

The catalytic filter is in all of the described methods functioning interchangeably through the suction and blowing action, causing thereby a self-cleaning process. The engine power loss becomes insignificant.

As in the example shown by FIG. 8 various catalytic reactive materials may be combined into a filter disc.

It may be also pointed out that the exhaust filter will also function as a spark-arrester, which may be of advantage in industrial applications, where sparking cannot be tolerated.

The possible remaining fuel residues within a porous ceramic filter may also be removed during the filtering process through additional burning by constant or intermittant methods.

FIG. 9 illustrates how the concept of the invention 'can be applied in general, without restriction to internal combustion engines, as for example to clean the exhaust fumes of furnaces, incinerators, or chemical reac- 'tors, represented as a combustion device 100. Conduit means 101 serves to pass the exhaust fumes of combustion device 100 into the filter device 102 of the invention, wherein the fumes are cleaned by reaction with the cyclically moving filter, as previously described. The purified exhaust is discharged from filter device 102 through conduit 103. Intake gas, such as air, enters filter device 102 through conduit means 104 to clean the filter areas contaminated by the exhaust, and this intake air, which passes through the filter in the direction opposite to the flow ofexhaust fumes therethrough, enters combustion device 100 through conduit 105. Thus, the filter will be continuously cleaned, at least of solid deposits, which will be returned to the combustion device for rebuming. With some types of catalytic filters it is possible to have chemical regeneration of the catalyst by the intake gas, be dispersing therein a suitable regenerating agent.

From the foregoing description, the artisan will appreciate that the invention is adaptable to numerous modifications and variations, that will become obvious from the given examples.

What is claimed is:

1. An apparatus for cleaning exhaust fumes from a combustion device which comprises a first conduit means defining a first flow path communicating with the combustion device to receive exhaust fumes outflowing therefrom; a second conduit means defining a second flow path communicating with said combustion device to deliver an intake gas flow thereto; a filter disposed for movement relative to said first and second conduit means and positioned to intercept said first and second flow paths, the area of the filter intercepted by said first flow path being operable to clean exhaust fumes flowing in a given direction through the filter and trap solid particle components thereof; the area of the filter intercepted by said second flow path being cleaned by the intake gas flowing in the opposite direction through the filter and removing trapped solid particles therefrom; such removed particles being carried by the intake gas into the combustion device; means for cyclically moving said filter to successively present for interception with said second flow path for cleaning those areas of the filter previously intercepted by said first flow path and to sucessively present cleaned filter areas for interception with said first flow path said filter being in the formof an endless belt and rotatable means supporting said belt and moving same through said first and second flow paths.

2. An apparatus for cleaning exhaust fumes from a combustion device which comprises a first conduit means defining a first flow path communicating with the combustion device to receive exhaust fumes outflowing therefrom; a second conduit means defining a second flow path communicating with said combustion device to deliver an intake gas flow thereto; a filter disposed for movement relative to said first and second conduit means and positioned to intercept said first and second flow paths, the area of the filter intercepted by said first flow path being operable to clean exhaust fumes flowing in a given direction through the filter and trap solid particle components thereof; the area of the filter intercepted by said second flow path being cleaned by the intake gas flowing in the opposite direction through the filter and removing trapped solid particles therefrom, such removed particles being carried by the intake gas into the combustion device; means for cyclically moving said filter to successively present for interception with said second flow path for cleaning those areas of the filter previously intercepted by said first flow path and to successively present cleaned filter areas for interception with said first flow path, said filter being porous and the porosity size of the filter 

1. An apparatus for cleaning exhaust fumes from a combustion device which comprises a first conduit means defining a first flow path communicating with the combustion device to receive exhaust fumes outflowing therefrom; a second conduit means defining a second flow path communicating with said combustion device to deliver an intake gas flow thereto; a filter disposed for movement relative to said first and second conduit means and positioned to intercept said first and second flow paths, the area of the filter intercepted by said first flow path being operable to clean exhaust fumes flowing in a given direction through the filter and trap solid particle components thereof; the area of the filter intercepted by said second flow path being cleaned by the intake gas flowing in the opposite direction through the filter and removing trapped solid particles therefrom; such removed particles being carried by the intake gas into the combustion device; means for cyclically moving said filter to successively present for interception with said second flow path for cleaning those areas of the filter previously intercepted by said first flow path and to sucessively present cleaned filter areas for interception with said first flow path said filter being in the form of an endless belt ; and rotatable means supporting said belt and moving same through said first and second flow paths.
 2. An apparatus for cleaning exhaust fumes from a combustion device which comprises a first conduit means defining a first flow path communIcating with the combustion device to receive exhaust fumes outflowing therefrom; a second conduit means defining a second flow path communicating with said combustion device to deliver an intake gas flow thereto; a filter disposed for movement relative to said first and second conduit means and positioned to intercept said first and second flow paths, the area of the filter intercepted by said first flow path being operable to clean exhaust fumes flowing in a given direction through the filter and trap solid particle components thereof; the area of the filter intercepted by said second flow path being cleaned by the intake gas flowing in the opposite direction through the filter and removing trapped solid particles therefrom, such removed particles being carried by the intake gas into the combustion device; means for cyclically moving said filter to successively present for interception with said second flow path for cleaning those areas of the filter previously intercepted by said first flow path and to successively present cleaned filter areas for interception with said first flow path, said filter being porous and the porosity size of the filter media decreasing in the exhaust fumes flow direction. 